TY - JOUR
T1 - Radical cation salts of BETS and ET with dicyanamidocuprate anions demonstrating metal-insulator and semiconductor–semiconductor transitions
AU - Kushch, Nataliya D.
AU - Kopotkov, Vyacheslav A.
AU - Shilov, Gennady V.
AU - Akimov, Alexander V.
AU - Tokarev, Sergey V.
AU - Yagubskii, Eduard B.
AU - Zverev, Vladimir N.
AU - Khasanov, Salavat S.
AU - Winter, Stephen M.
AU - Jeschke, Harald O.
N1 - Funding Information:
We thank Prof. Akira Miyazaki for providing BETS used in the work and Dr. L. I. Buravov for test measurements of R(T) of some samples. The work was supported by the RFBR grants No. 17-03-00167 and 18-02-00280. The part of the work was done on the topic of the State task No. AAAA-A19-111902390079-8 with using of the Computational and Analytical Center for Collective Use of the IPCP RAS tool base.
Funding Information:
We thank Prof. Akira Miyazaki for providing BETS used in the work and Dr. L. I. Buravov for test measurements of R(T) of some samples. The work was supported by the RFBR grants No. 17-03-00167 and 18-02-00280 . The part of the work was done on the topic of the State task No. AAAA-A19-111902390079-8 with using of the Computational and Analytical Center for Collective Use of the IPCP RAS tool base.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/10/1
Y1 - 2020/10/1
N2 - Electrocrystallization of bis(ethylenedithio)tetraselenafulvalene (BETS) and bis(ethylenedithio)tetrathiafulvalene (ET) in the presence of an electrolyte (Ph4P)[Cu(dca)]3⋅H2O [(dca) = N(CN)2] has been studied using different solvents. A new organic metal (BETS)2Cu(dca)3 (1), and the first radical cation salt with 3D dicyanamidocuprate anion, incorporating both diamagnetic Cu1+ and paramagnetic Cu2+atoms, (ET)2Cu1.8(dca)4 (2) have been obtained. Crystal structure, conducting properties of both salts, as well as the electronic structure of 2 and its structural analog (ET)2CuMn(dca)4 (3) were analysed. The salts 1 and 2 have layered structures. In contrast to the BETS radical cation salt 1, complex 2 is characterized by the presence of a 3D polymeric anion built into the ET radical cation layers. At ambient pressure, the resistance of the crystals 1 shows semimetal behaviour down to 30 K. Below 30 K, the resistance sharply increases and the sample becomes insulating. The application of a pressure of about 3 kbar suppresses the metal-insulator transition. The salt 2 undergoes a semiconductor I - semiconductor II phase transition, which is manifested by a jump in the resistance and a hysteresis in the R(T) curves in a very large temperature range (185 – 250 K). The phase transition is accompanied by changes in the charge state of the ET molecules, and notable structure changes in the anion layer, especially in the environment of Cu2+. For the salt 3 the calculated selfconsistent charges show upon cooling a sharp increase of charge order between 291 K and 285 K.
AB - Electrocrystallization of bis(ethylenedithio)tetraselenafulvalene (BETS) and bis(ethylenedithio)tetrathiafulvalene (ET) in the presence of an electrolyte (Ph4P)[Cu(dca)]3⋅H2O [(dca) = N(CN)2] has been studied using different solvents. A new organic metal (BETS)2Cu(dca)3 (1), and the first radical cation salt with 3D dicyanamidocuprate anion, incorporating both diamagnetic Cu1+ and paramagnetic Cu2+atoms, (ET)2Cu1.8(dca)4 (2) have been obtained. Crystal structure, conducting properties of both salts, as well as the electronic structure of 2 and its structural analog (ET)2CuMn(dca)4 (3) were analysed. The salts 1 and 2 have layered structures. In contrast to the BETS radical cation salt 1, complex 2 is characterized by the presence of a 3D polymeric anion built into the ET radical cation layers. At ambient pressure, the resistance of the crystals 1 shows semimetal behaviour down to 30 K. Below 30 K, the resistance sharply increases and the sample becomes insulating. The application of a pressure of about 3 kbar suppresses the metal-insulator transition. The salt 2 undergoes a semiconductor I - semiconductor II phase transition, which is manifested by a jump in the resistance and a hysteresis in the R(T) curves in a very large temperature range (185 – 250 K). The phase transition is accompanied by changes in the charge state of the ET molecules, and notable structure changes in the anion layer, especially in the environment of Cu2+. For the salt 3 the calculated selfconsistent charges show upon cooling a sharp increase of charge order between 291 K and 285 K.
KW - Conductivity
KW - Crystal and electronic structure
KW - Dicyanamidocuprate
KW - Phase transition
KW - Pressure effect
KW - Radical cation salt
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U2 - 10.1016/j.poly.2020.114705
DO - 10.1016/j.poly.2020.114705
M3 - Article
AN - SCOPUS:85089072107
SN - 0277-5387
VL - 189
JO - Polyhedron
JF - Polyhedron
M1 - 114705
ER -